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2-digit Square
A 2-Digit number is squared. When this 2-digit number is reversed and squared, the difference between the squares is also a square. What is the 2-digit number?
Consecutive Squares
The squares of any 8 consecutive numbers can be arranged into two sets of four numbers with the same sum. True of false?
Plus Minus
Can you explain the surprising results Jo found when she calculated the difference between square numbers?
Age 14 to 16 Short
Challenge Level
Without calculating the five products below, put them in order of size, from smallest to largest.
| 210$\times$190 | 198$\times$202 | 200$\times$200 |
| 195$\times$205 | 186$\times$214 |
This problem is taken from the World Mathematics Championships
You can find more short problems, arranged by curriculum topic, in our short problems collection.
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NRICH is part of the family of activities in the Millennium Mathematics Project.
NRICH is part of the family of activities in the Millennium Mathematics Project.